CD30 is a 120-kDa type I transmembrane protein that is expressed on activated B and T lymphocytes in healthy individuals. Expression of CD30 has been observed in several nonmalignant disorders, including lymphomatoid papulosis, and in virally transformed B and T cells. CD30 is also expressed in several types of malignancies, including Hodgkin's disease, anaplastic large-cell lymphoma (ALCL), immunoblastic lymphoma, multiple myeloma, adult T-cell lymphoma leukemia, mycosis fungoides, germ-cell malignancies, and thyroid carcinoma. Soluble CD30 is detected at low levels in the sera of healthy individuals and in individuals infected with one of several different viruses, including hepatitis B and C, human immunodeficiency virus (HIV), and Epstein-Barr virus (EBV), and at higher levels, in individuals with systemic lupus erythematosis, rheumatoid arthritis, and Hashimoto's thyroiditis. Elevated levels of soluble CD30 in sera from patients who have anaplastic large-cell lymphoma or Hodgkin's disease have been reported to correlate with a poor prognosis (Younes & Kadin, 2003, Journal of Clinical Oncology, 21(18):3526-3534; Al-Shamkhani, 2004, Current Opinion in Pharmacology, 4:355-359).
CD30L (CD153) is a type II transmembrane protein that belongs to the TNF family, and is expressed in a wide variety of hematopoietic cells including activated T cells, activated macrophages, B cells, neutrophils, eosiniphils, and mast cells. Engagement of CD30L on these cells with CD30 on the surface of H-RS cells regulates growth and activation, as well as epithelial cells and Hassall's corpuscles in the thymus medulla. A number of hematopoietic tumors also express CD30L, including chronic lymphocytic leukemia (CLL), follicular B-cell lymphoma, hairy cell leukemia, T-cell lymphoblastic lymphoma, and adult T-cell leukemia lymphoma (Younes & Kadin, 2003, Journal of Clinical Oncology, 21(18):3526-3534; Al-Shamkhani, 2004, Current Opinion in Pharmacology, 4:355-359, entirely incorporated by reference).
A common class of therapeutic proteins are monoclonal antibodies. A number of favorable properties of antibodies, including but not limited to specificity for target, ability to mediate immune effector mechanisms, and long half-life in serum, make antibodies powerful therapeutics. A number of antibodies that target CD30 are approved or in clinical trials for the treatment of a variety of cancers. There are also anti-CD30 antibodies in development. Despite the favorable differential expression of CD30 on tumor cells versus normal cells and the number of anti-CD30 antibodies in development, anti-CD30 antibodies have not been successful clinically.
There are a number of possible mechanisms by which antibodies destroy tumor cells, including anti-proliferation via blockage of needed growth pathways, intracellular signaling leading to apoptosis, enhanced down regulation and/or turnover of receptors, CDC, ADCC, ADCP, and promotion of an adaptive immune response (Cragg et al., 1999, Curr Opin Immunol 11:541-547; Glennie et al., 2000, Immunol Today 21:403-410, both entirely incorporated by reference). Anti-tumor efficacy may be due to a combination of these mechanisms, and their relative importance in clinical therapy appears to be cancer dependent.
A promising means for enhancing the anti-tumor potency of antibodies is via enhancement of their ability to mediate cytotoxic effector functions such as ADCC, ADCP, and CDC. The importance of FcγR-mediated effector functions for the anti-cancer activity of antibodies has been demonstrated in mice (Clynes et al., 1998, Proc Natl Acad Sci USA 95:652-656; Clynes et al., 2000, Nat Med 6:443-446, both entirely incorporated by reference), and the affinity of interaction between Fc and certain FcγRs correlates with targeted cytotoxicity in cell-based assays (Shields et al., 2001, J Biol Chem 276:6591-6604; Presta et al., 2002, Biochem Soc Trans 30:487-490; Shields et al., 2002, J Biol Chem 277:26733-26740, each of which is incorporated by reference in its entirety). Additionally, a correlation has been observed between clinical efficacy in humans and their allotype of high (V158) or low (F158) affinity polymorphic forms of FcγRIIIa (Cartron et al., 2002, Blood 99:754-758; Weng & Levy, 2003, Journal of Clinical Oncology, 21:3940-3947, both entirely incorporated by reference). Together these data suggest that an antibody that is optimized for binding to certain FcγRs may better mediate effector functions and thereby destroy cancer cells more effectively in patients. The balance between activating and inhibiting receptors is an important consideration, and optimal effector function may result from an antibody that has enhanced affinity for activation receptors, for example FcγRI, FcγRIIa/c, and FcγRIIIa, yet reduced affinity for the inhibitory receptor FcγRIIb. Furthermore, because FcγRs can mediate antigen uptake and processing by antigen presenting cells, enhanced FcγR affinity may also improve the capacity of antibody therapeutics to elicit an adaptive immune response. With respect to CD30, ADCC has been implicated as an important effector mechanism for the anti-tumor cytotoxic capacity of some anti-CD30 antibodies (Bleeker et al., 2004, J. Immunol. 173(7):4699-707; Bier et al., 1998, Cancer Immunol Immunother 46:167-173, both entirely incorporated by reference).
Some success has been achieved at obtaining Fc variants with selectively enhanced binding to FcγRs, and in some cases these Fc variants have been shown to provide enhanced potency and efficacy in cell-based effector function assays. See, for example, U.S. Pat. No. 5,624,821, PCT WO 00/42072, U.S. Pat. No. 6,737,056, U.S. Ser. No. 10/672,280, PCT US03/30249, and U.S. Ser. No. 10/822,231, and U.S. Ser. No. 60/627,774, filed Nov. 12, 2004 and entitled “Optimized Fc Variants”, and references cited therein, each of which is incorporated by reference in its entirety. Enhanced affinity of Fc for FcγR has also been achieved using engineered glycoforms generated by expression of antibodies in engineered or variant cell lines (Umaña et al., 1999, Nat Biotechnol 17:176-180; Davies et al., 2001, Biotechnol Bioeng 74:288-294; Shields et al., 2002, J Biol Chem 277:26733-26740; Shinkawa et al., 2003, J Biol Chem 278:3466-3473, each of which is incorporated by reference in its entirety).
The present invention provides variants of anti-CD30 antibodies that provide enhanced effector function. A variety of modifications are described that provide anti-CD30 antibodies with optimized clinical properties. A broad array of applications of the anti-CD30 antibodies are contemplated.